JP4004775B2 - Asphalt pavement and asphalt pavement structure with a function to suppress the rise in road surface temperature - Google Patents

Description

【０００４】
表１によると、真夏の一日において水透過機能を有しない密粒度アスファルト舗装体と水透過機能を有する開粒度アスファルト舗装体が略同様の表面温度であって、自然地盤より高温となることを示している。
又、略同様の表面温度である２種類のアスファルト舗装体中、自然地盤の一機能である水透過機能を有する開粒度アスファルト舗装体の様に、多孔質体で水透過機能を有する透水性舗装体も開発されているが、この透水性舗装体は粗粒原料で隙間（空隙）が大きく水透過作用が大きい反面、毛細管現象（毛管現象）による揚水作用は小さく、舗装路盤より吸い上げた水分は舗装体途中で止まって舗装表面まで到達しなかった。
透水性舗装体の様に水透過機能を有するだけでは、水収支を自然に近づけたり、路面温度の上昇を抑制することが充分でなく、ヒートアイランド現象を抑制するまでには至らなかった。
【０００５】
又、降雨があってアスファルト舗装体の表面が湿潤状態の場合、表面の水分が気化し表面温度の上昇が一時期低減されることが一般的に知られている。
【０００６】
一方、ガラス原料となる珪砂は、鉱山から採掘された原鉱を精製し製造しているが、珪砂精製工程（主に水洗分級）で微粒珪砂が発生し、特殊用途に一部の微粒珪砂が利用されているが、大半は産廃汚泥として埋め立て処分されており、処分が社会問題化しつつある。
【０００７】
【発明が解決しようとする課題】
本発明は、自然地盤の一機能である水透過機能単独では舗装の路面温度上昇を抑制することが不可能で、水分が継続して気化し舗装体から気化熱を奪う機能を人工的に継続して付与することが困難な課題に対して、水透過機能を有する舗装体であって、水分の気化熱を利用して、継続的に舗装体の温度上昇を抑制できる多孔質表層（路面構造における表層）として、毛管現象による揚水機能を有する多孔質表層を提供し、同時に、多孔質表層中、ガラス原料を得る珪砂精製過程において発生する産業副産物である微粒珪砂を充填した多孔質表層の路面温度の上昇抑制機能を備えたアスファルト舗装体およびアスファルト舗装路面構造を提供する。
【０００８】
【課題を解決するための手段】
本発明は、上記従来技術に基づく、ヒートアイランド現象の抑制に有効な対策が見出せなかった課題、及び微粒珪砂の処分が困難化しつつある課題に鑑み、水透過機能を有し容積百分率で15〜25％の空隙を有するアスファルト混合物を用いた多孔質表層において、充填状態で保水性を有すると共に透水性、揚水性を有する、粒径を１０μｍ以上とし且つ平均粒径約80〜200 μｍとした微粒珪砂を、舗装体の体積１m³につき80〜160kg 空隙内に充填して、充填後の微粒珪砂を未固化状態とすることにより、舗装体内部に多数の微細な連続空隙を生成させ、生成された連続空隙で舗装体の下面から上面への揚水機能を具備させ、毛管現象で表面に揚水された水分を蒸発させ、周囲から気化熱を奪って舗装表面を冷却し、且つ、充填物に産業副産物として廃棄処分されている微粒珪砂を使用して環境保全を図る様にして、上記課題を解決する。
【０００９】
【発明の実施の形態】
以下、本発明の微粒珪砂を充填した路面温度の上昇抑制機能を備えたアスファルト舗装体（舗装路面構造における多孔質表層）の実施の形態について、添付する実験データおよび図面に基づき説明する。
【００１０】
本発明のアスファルト舗装体は主に歩行者系道路または軽車輌通過道路など（重量付加が軽度な道路）に施工され、図１に示す様に、舗装路面構造は下層の路盤１と上層（表層）のアスファルト舗装体２から成り、開粒度アスファルト（骨材３、3a…）による多孔質のアスファルト舗装体２の空隙に表面（上面）から微粒珪砂４、4a…を全体的に充填したものである。
【００１１】
アスファルト舗装体２の具体例としては、骨材３、3a…とアスファルトの混合物で水透過機能を有する開粒度アスファルトによりアスファルト舗装体２の基体を構成し、通常施工例である容積百分率で15〜25％の空隙を有する多孔質体のアスファルト舗装体２の表面から微粒珪砂４、4a…を充填している。
微粒珪砂４、4a…の充填方法としては、締め固め後のアスファルト舗装体２の表面に微粒珪砂４、4a…を散布し、アスファルト舗装体２の空隙内に自然落下させたり、表面に振動付与したり、水散布し、微粒珪砂４、4a…をアスファルト舗装体２の内部空隙に落下させ、下面（路盤１との接触面）から表面の全空隙に微粒珪砂４、4a…を充填し、空隙に微細な連続空隙を形成している。
【００１２】
アスファルト舗装体２の充填物とした微粒珪砂４、4a…は過小粒体、粉体だと連続空隙を閉鎖し、過大粒体では水透過機能を有していても、保水性が低かったり、揚水性（毛管現象）が無いため、粒径１０μｍ以上のものを使用する。
微粒珪砂４、4a…は後述の様に瀬戸地区で排出されているもの（平均粒径80〜200 μｍ）を使用しているが、他地区のものでも勿論使用可能である。
そして、水透過機能を有したアスファルト舗装体２として一般的な容積百分率で15〜25％の空隙を有する多孔質のアスファルト舗装体２に、微粒珪砂４、4a…を下層から上層までの全体に充填した処、空隙率１５％ではアスファルト舗装体２の体積１m³につき８０kgの微粒珪砂４、4a…が充填され、空隙率２５％では１６０kgの微粒珪砂４、4a…を充填でき、微粒珪砂４、4a…の粒径相違による充填量に大差はなかった。
【００１３】
路盤１は通常舗装の路盤材料または透水性舗装の路盤材料、例えば、粒度調整砕石またはクラッシャーランが使用され、強度、耐久性の他、適度な透水能、貯水能を有する路盤が好ましい。
本発明ではアスファルト舗装体２による保水、揚水、蒸発作用を向上させたり、持続させるために、路盤１にも保水機能、揚水機能を有するものとしており、具体的には、通常の路盤に対して、アスファルト舗装体２に使用した充填物と同一物（微粒珪砂４、4a…）を充填し、路盤１の保水性、揚水性をアスファルト舗装体２と同等に、或いは通常比で向上させている。
【００１４】
尚、路盤１を含むアスファルト舗装体２内に充填した微粒珪砂４、4a…が降下し、アスファルト舗装体２の空隙表面に微粒珪砂４、4a…が存在しなくなった時には、アスファルト舗装体２の表面に微粒珪砂４、4a…を散布して空隙に補充充填し、連続空隙を表面まで再生する。
【００１５】
以下、本発明の路面温度の上昇抑制機能を備えたアスファルト舗装体の有効性を確認した実験（実施例）を行ったので、説明する。
先ず、実施例において使用した微粒珪砂４、4a…の品質を表２に表示する。
【００１６】
【表２】

【００１７】
尚、微粒珪砂４、4a…は、愛知県瀬戸市を中心とする国内最大の珪砂産業によって同地区で年間約20万トンが排出され、一部が特殊用途に活用されているが全体量の約70％が採掘跡地に埋め戻し処分されている。
現在瀬戸地区で排出されている各種の微粒珪砂４、4a…の品質測定結果について、表３に各項目の最大値および最小値を表示する。
【００１８】
【表３】

【００１９】
実施例において使用した微粒珪砂４、4a…の保水性を表４に表示する。
保水性試験に使用された試験体は、直径7.5cm で高さ200cm の円柱状の形状寸法の容器に微粒珪砂４、4a…を充填したものであり、乾燥状態の微粒珪砂４、4a…を自然落下により容器に充填した後、上面より8リットル の水道水を注水し、注水完了後、底面より2cm のみ水に浸す水浸条件で２週間放置後の含水比 (水分／試験体（微粒珪砂４、4a…）の乾燥重量) を底面より高さ5cm を基準として、上方に10cm間隔で測定したものである。
表４では比較のため細骨材（砂）を充填した試験体についても同様の実験を行った結果を併せて表示している。
尚、表５に保水性試験に使用した微粒珪砂４、4a…と細骨材（砂）の品質を表示している。
【００２０】
【表４】

【００２１】
【表５】

【００２２】
表４の保水性試験の測定結果に示す様に、各高さ位置において微粒珪砂４、4a…は細骨材の２〜３倍程度（中間位置では７〜８倍程度）の含水比を有し、且つ、細骨材は高くなるに連れて含水比が低下した後、一定化傾向を示して高さ25cmで含水比10％程度であるのに比して、微粒珪砂４、4a…は数十cm程度の高さまで含水比は同等で、それ以上の高さで低下傾向を示し、高さ75cmにおいても含水比40％程度を有している。
【００２３】
本発明のアスファルト舗装体２の施工高さは数cmから２０cm程度（５cmと１０cmが多い）であり、この範囲では微粒珪砂４、4a…が数倍の含水比を有し、路盤３を含んだ施工高さは数十cm程度（アスファルト５cmを含む合計５５〜６０cmが多い）であり、この範囲では微粒珪砂４、4a…が数倍以上の含水比を有している。
この試験結果によると、微粒珪砂４、4a…を充填した試験体は高い保水性を有し、例えば、密集した微粒珪砂４、4a…は微細な連続空隙を有していることにより、大きな毛管現象や表面張力現象で、水分の上昇作用を有したり、水分の流出を抑止して、高い保水性を有している。
尚、表４の保水性試験の微粒珪砂４、4a…は表２、表５に示す平均粒径８１μｍのものであって、現実に排出されている平均粒径約２００μｍの測定値は表示しなかったが、充分な保水性を有していた。
【００２４】
次に本発明に係る微粒珪砂４、4a…を充填した多孔質表層（路面温度の上昇抑制機能を備えたアスファルト舗装体）の作用確認として行った、出願人の自社敷地内の屋外実験場に構築した試験道路での測定結果を説明する。
【００２５】
表６は試験母体となる多孔質表層および無孔質表層の仕様を示すと共に、試験道路の欄に図２に示した試験道路断面図と仕様の関係を示し、図２は試験道路として構築した５種類（自然土の１種類を含む）の舗装構造を示す断面図である。図２（ａ）および（ｂ）は表６第１、２段の仕様のアスファルト舗装体２（空隙率２５％または１５％）に表２に示した微粒珪砂４、4a…を充填した多孔質表層および砕石路盤材からなる路面温度の上昇抑制機能を有する舗装体である。
図２（ｃ）は従来の一般的な舗装としての密粒度アスファルト混合物の舗装体（透水性なし）、図２（ｄ）は従来の一般的な舗装としての開粒度アスファルト混合物の透水性舗装体（図２（ａ）（ｂ）の基体であって微粒珪砂４、4a…を充填していない舗装体）、図２（ｅ）は現地盤の自然土であり、これらを比較測定の対象とした。
【００２６】
【表６】

【００２７】
路面温度の上昇抑制効果の実測を目的として平成13年８月22日より同年８月30日にかけて測定した結果を表７に、８月22日、23日の測定結果を表８、９に夫々表示する。
【００２８】
【表７】

【００２９】
【表８】

【００３０】
【表９】

【００３１】
表７〜９の測定結果に基づいて各舗装体の路面温度の上昇抑制能力の比較を行うと、本発明の微粒珪砂４、4a…を充填した多孔質表層を用いた路面温度の温度上昇抑制機能を有する舗装体（太実線、破線）では、従来の一般的な密粒度アスファルト舗装体（細実線）及び開粒度アスファルト舗装体( 透水性アスファルト舗装体) （点線）と比較して、温度上昇を抑制できた。
【００３２】
例えば、最高温度では、空隙率25％の開粒度アスファルト舗装体に微粒珪砂４、4a…を舗装体体積１m³につき160kg 充填した舗装体で路面の最高温度を16℃低下、空隙率15％の開粒度アスファルト舗装体に微粒珪砂４、4a…を舗装体体積１m³につき80kg充填した舗装体で8 ℃低下させることができた。
又、温度上昇抑制の持続では、本発明の微粒珪砂４、4a…を充填した多孔質表層を用いた路面温度の温度上昇抑制機能を有する舗装体では、何れの測定日においても一般的な密粒度アスファルト舗装体ならびに開粒度アスファルト舗装体( 透水性アスファルト舗装体) より常に低い温度となり、路面温度の上昇抑制効果を持続的に発現できた。
【００３３】
【発明の効果】
要するに本発明は、水透過機能を有する多孔質のアスファルト舗装体２において、粒径を１０μｍ以上とし且つ平均粒径約 80 〜 200 μｍと成して、充填状態で保水性を有すると共に透水性、揚水性を有する微粒珪砂４、 4a …をアスファルト舗装体２の空隙に充填して、充填後の微粒珪砂４、 4a …を未固化状態としたので、水分は路面構造における多孔質表層であるアスファルト舗装体２内の空隙に充填された微粒珪砂４、 4a …により形成された連続微細空隙に保水され、アスファルト舗装体２の表面付近で水分蒸発に伴って周辺から気化熱を奪うことにより、多孔質表層の表面温度の上昇を抑制することが出来、更に、多孔質表層内に形成された連続微細空隙で毛管現象（揚水作用）による水分の上昇移動作用が継続的に発生することにより、水分の蒸発、周辺からの気化熱奪取、表面温度の上昇抑制を継続させることが出来、よってヒートアイランド現象を抑制することができる。
【００３４】
微粒体は１０μｍ以上の粒径と成したので、アスファルト舗装体２内の空隙を閉塞せず、保水、揚水機能を有する連続微細空隙を容易に形成することが出来る。
【００３５】
微粒体を微粒珪砂４、4a…と成したので、産廃汚泥である微粒珪砂４、4a…の利用で環境保全を図ることが出来る。
【００３６】
微粒珪砂４、4a…は平均粒径80〜200 μｍと成したので、一般的に大量に廃棄処分されている微粒珪砂４、4a…を活用することが出来る。
【００３７】
多孔質のアスファルト舗装体２は容積百分率で15〜25％の空隙を有するものとしたので、一般的な舗装手段に対しても本願発明を実施することが出来る。
【００３８】
アスファルト舗装体２の体積１m³につき80〜160kg の微粒珪砂４、4a…を空隙に充填したので、アスファルト舗装体２の表面まで微粒珪砂４、4a…を充填して蒸発作用を活発化させることが出来る。
【００３９】
舗装路面構造が下層の路盤１と請求項１、２又は３記載の表層のアスファルト舗装体２から成り、路盤１は保水性を有するものと成したので、路盤１もアスファルト舗装体２と同様の保水機能を有し、アスファルト舗装体２で蒸発、保水、揚水される水分を路盤１からも容易に補給して、蒸発散作用を継続的に長期に達成することが出来る。
【００４０】
路盤１にアスファルト舗装体２と同一の微粒体又は微粒珪砂４、4a…を充填したので、路盤１とアスファルト舗装体２の連続微細空隙を境目なく形成して、保水、揚水機能の連続性を持たせることが出来たり、路盤１内で微粒体又は微粒珪砂４、4a…が降下しても、アスファルト舗装体２表面へ微粒体又は微粒珪砂４、4a…を補給することにより、路盤１の保水機能を容易に維持、再生することが出来る。
【００４１】
水透過機能を有する多孔質のアスファルト舗装体２の形成後、アスファルト舗装体２の表面に鉱物質の微粒体又は微粒珪砂４、4a…を散布し、表面側から振動付与したり、表面に水散布し、アスファルト舗装体２の空隙に微粒体又は微粒珪砂４、4a…を充填する様にしたので、アスファルト舗装体２に微粒体又は微粒珪砂４、4a…を簡単に充填することが出来る等その実用的効果甚だ大である。
【図面の簡単な説明】
【図１】本発明に係る路面構造の概略構成を示す断面図である。
【図２】各種試験道路の構造を示す断面図である。
【符号の説明】
１ 路盤
２ アスファルト舗装体
３、3a… 骨材
４、4a… 微粒珪砂[0001]
BACKGROUND OF THE INVENTION
The present invention is water-retentive in the asphalt pavement, the pumping is imparted, pavement evaporated from the surface, asphalt pavement having a rise suppression function of road surface temperature was set to suppress the surface temperature rise and asphalt pavement Concerning structure .
[0002]
[Prior art]
In recent years, one of the urban environmental problems is the heat island phenomenon represented by an increase in the number of tropical nights. This is thought to be due to an increase in exhaust heat due to human activities and the blockage of atmospheric circulation by buildings, but the surface of the ground (various water impermeability, water permeation possible, black, etc.) One of the reasons is that the water balance is different from the natural nature due to being covered with pavement. The surface temperature of the road pavement in midsummer, especially the road surface temperature of the asphalt pavement, can reach 60 ° C or more because it absorbs heat from the sun's solar radiation because it is black. The surface temperature tends to rise.
Table 1 attached below is a dense particle size asphalt pavement that is a surface layer that does not have a midsummer day temperature and water permeation function, an open particle size (water permeability) asphalt pavement that is a porous surface layer that has a water permeation function, and This is a record of changes in the surface temperature of natural soil.
[0003]
[Table 1]

[0004]
According to Table 1, the dense grained asphalt pavement that does not have a water permeation function and the open grain asphalt pavement that has a water permeation function at substantially the same surface temperature in the day of midsummer Show.
In addition, among two types of asphalt pavement with approximately the same surface temperature, porous permeable pavement with water permeation function, such as open-grain asphalt pavement with water permeation function which is a function of natural ground Although the body is also developed, this water-permeable pavement is a coarse raw material with large gaps (voids) and a large water permeation effect, but the pumping action due to capillary action (capillary phenomenon) is small, and the water sucked up from the paved roadbed is It stopped in the middle of the pavement and did not reach the pavement surface.
Just having a water permeation function like a water-permeable pavement does not sufficiently bring the water balance closer to the natural environment or suppress the increase in road surface temperature, and does not lead to the suppression of the heat island phenomenon.
[0005]
Further, it is generally known that when there is rain and the surface of the asphalt pavement is wet, the surface moisture is vaporized and the rise in surface temperature is reduced for a time.
[0006]
On the other hand, silica sand, which is a raw material for glass, is produced by refining the raw ore extracted from the mine, but fine silica sand is generated in the silica sand refining process (mainly washing classification), and some fine silica sand is used for special applications. Although it is used, most of it is landfilled as industrial waste sludge, and disposal is becoming a social problem.
[0007]
[Problems to be solved by the invention]
In the present invention, the water permeation function alone, which is a function of natural ground, cannot suppress the increase in road surface temperature of the pavement, and the function of continuously evaporating moisture and removing the heat of vaporization from the pavement is continued. A porous surface layer (road surface structure) that has a water permeation function and that can suppress the temperature rise of the pavement continuously by utilizing the heat of vaporization of moisture. The surface of the porous surface layer filled with fine silica sand, which is an industrial by-product generated during the silica sand purification process to obtain glass raw materials in the porous surface layer Provided is an asphalt pavement and an asphalt pavement structure having a function of suppressing temperature rise.
[0008]
[Means for Solving the Problems]
The present invention has a water permeation function and has a volume percentage of 15 to 25 in view of the problem that an effective measure for suppressing the heat island phenomenon based on the above-mentioned conventional technology has not been found and the problem that disposal of fine silica sand is becoming difficult. % Fine silica sand having a water content in the filled state and water permeability and water pumping, having a particle size of 10 μm or more and an average particle size of about 80 to 200 μm, in a porous surface layer using an asphalt mixture having a% void Was created by creating a large number of fine continuous voids inside the pavement by filling it into a void of 80 to 160 kg per 1 m ³ of pavement and making the fine silica sand after filling into an unsolidified state . It is equipped with a pumping function from the lower surface to the upper surface of the pavement with continuous voids, evaporates the water pumped to the surface by capillary action, cools the pavement surface by removing vaporization heat from the surroundings, and industrial by-products in the filling As abandoned The above problems are solved by using the fine silica sand that has been disposed of to protect the environment.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an embodiment of an asphalt pavement (porous surface layer in a paved road surface structure) having a function of suppressing an increase in road surface temperature filled with fine silica sand according to the present invention will be described with reference to the attached experimental data and drawings.
[0010]
The asphalt pavement of the present invention is mainly constructed on pedestrian roads or light vehicle passing roads (roads with light weight addition). As shown in FIG. 1, the paved road surface structure is composed of a lower roadbed 1 and an upper layer (surface layer). ) Of asphalt pavement 2 and is filled with fine silica sand 4, 4a ... from the surface (upper surface) into the pores of porous asphalt pavement 2 made of open-graded asphalt (aggregate 3, 3a ...). is there.
[0011]
As a concrete example of the asphalt pavement 2, the base of the asphalt pavement 2 is composed of a mixture of aggregates 3, 3a... And asphalt with an open-graded asphalt having a water permeation function. Fine silica sand 4, 4a... Is filled from the surface of the porous asphalt pavement 2 having 25% voids.
As for the method of filling the fine silica sand 4, 4a ..., the fine silica sand 4, 4a ... is sprayed on the surface of the compacted asphalt pavement 2 to let it fall naturally into the space of the asphalt pavement 2 or to give vibration to the surface. Or by spraying with water, dropping the fine silica sand 4, 4a ... into the internal space of the asphalt pavement 2, filling the entire space from the bottom surface (contact surface with the roadbed 1) with the fine silica sand 4, 4a ... Fine continuous voids are formed in the voids.
[0012]
The fine silica sand 4, 4a ... used as a filler for the asphalt pavement 2 is a small particle, which closes the continuous void when it is a powder. Even if the large particle has a water permeation function, its water retention is low, for pumping of (capillarity) it is not, to use more than a particle size 10 [mu] m.
As described later, fine silica sand 4, 4a... Is discharged from the Seto district (average particle size of 80 to 200 μm), but can be used in other districts as well.
And, as the asphalt pavement 2 having a water permeation function, the porous asphalt pavement 2 having a void of 15 to 25% in a general volume percentage, and fine silica sand 4, 4a. When the filling rate is 15%, 80 kg of fine silica sand 4, 4a ... is filled per 1 m ³ of asphalt pavement 2 and when the porosity is 25%, 160 kg of fine silica sand 4, 4a ... can be filled. There was no significant difference in the filling amount due to the difference in particle diameter of 4a.
[0013]
The roadbed 1 is usually a roadbed material for pavement or a roadbed material for water-permeable pavement, such as a particle size-adjusted crushed stone or crusher run, and is preferably a roadbed having appropriate water permeability and water storage capacity in addition to strength and durability.
In the present invention, in order to improve or maintain the water retention, pumping, and evaporation by the asphalt pavement 2, the roadbed 1 also has a water retention function and a pumping function. The same material (fine silica sand 4, 4a ...) used for the asphalt pavement 2 is filled, and the water retention and pumping capacity of the roadbed 1 is improved to the same level as the asphalt pavement 2 or at a normal ratio. .
[0014]
When the fine silica sand 4, 4 a... Filled in the asphalt pavement 2 including the roadbed 1 descends and no fine silica sand 4, 4 a... Exists in the gap surface of the asphalt pavement 2, the asphalt pavement 2 Spray fine silica sand 4, 4a ... on the surface to replenish and fill the voids, and regenerate the continuous voids to the surface.
[0015]
Hereafter, since the experiment (Example) which confirmed the effectiveness of the asphalt pavement provided with the rise suppression function of the road surface temperature of this invention was performed, it demonstrates.
First, the quality of the fine silica sand 4, 4a used in the examples is displayed in Table 2.
[0016]
[Table 2]

[0017]
In addition, about 200,000 tons of fine silica sand 4, 4a ... are discharged annually in the same area by the largest domestic silica industry in Seto City, Aichi Prefecture, and some are used for special purposes. About 70% is backfilled at the mining site.
Table 3 shows the maximum and minimum values of each item for the quality measurement results of various fine silica sands 4, 4a ... currently discharged in the Seto district.
[0018]
[Table 3]

[0019]
Table 4 shows the water retention of the fine silica sands 4, 4a... Used in the examples.
The specimen used for the water retention test is a container with a cylindrical shape with a diameter of 7.5 cm and a height of 200 cm filled with fine silica sand 4, 4a ... After filling the container with natural fall, inject 8 liters of tap water from the top surface, and after water injection is completed, leave it for 2 weeks under water immersion conditions (water / test specimen (fine silica sand). 4, 4a...)) Was measured at intervals of 10 cm upward with respect to a height of 5 cm from the bottom.
Table 4 also shows the results of a similar experiment performed on a specimen filled with fine aggregate (sand) for comparison.
Table 5 shows the quality of the fine silica sand 4, 4a... And the fine aggregate (sand) used in the water retention test.
[0020]
[Table 4]

[0021]
[Table 5]

[0022]
As shown in the measurement results of the water retention test in Table 4, the fine silica sand 4, 4a ... has a water content ratio of about 2 to 3 times that of fine aggregates (about 7 to 8 times at the intermediate position) at each height position. However, the fine silica sand 4, 4a ... is more stable than the 25% height and the water content ratio is about 10% after the water content ratio decreases as the fine aggregate increases. The water content ratio is the same up to a height of about several tens of centimeters, and the water content ratio tends to decrease at heights higher than that. Even at a height of 75 cm, the water content ratio is about 40%.
[0023]
The construction height of the asphalt pavement 2 of the present invention is about several centimeters to about 20 centimeters (5 centimeters and 10 centimeters are large). In this range, the fine silica sand 4, 4 a. The construction height is about several tens of centimeters (the total is 55 to 60 cm including 5 cm of asphalt), and in this range, the fine silica sand 4, 4 a.
According to this test result, the specimen filled with the fine silica sand 4, 4 a has high water retention. For example, the dense fine silica sand 4, 4 a. Phenomenon and surface tension phenomenon, it has a high water retention effect by having an effect of increasing moisture or preventing outflow of moisture.
In addition, the fine silica sands 4, 4a... In the water retention test in Table 4 are those having an average particle diameter of 81 .mu.m shown in Tables 2 and 5, and the measured value of the average particle diameter of about 200 .mu.m actually discharged is indicated. Although there was no, it had sufficient water retention.
[0024]
Next, in the outdoor experiment site on the applicant's own premises, which was confirmed as the action of the porous surface layer (asphalt pavement with a function to suppress the rise in road surface temperature) filled with the fine silica sand 4, 4a ... The measurement results on the constructed test road will be explained.
[0025]
Table 6 shows the specifications of the porous surface layer and the non-porous surface layer as the test matrix, and shows the relationship between the test road cross-sectional view shown in FIG. 2 and the specifications in the test road column, and FIG. 2 is constructed as the test road. It is sectional drawing which shows five types (including 1 type of natural soil) pavement structure. 2 (a) and 2 (b) show a porous structure in which the asphalt pavement 2 (porosity 25% or 15%) of the specifications in the first and second stages of Table 6 is filled with the fine silica sand 4, 4a. It is a pavement having a function of suppressing an increase in road surface temperature comprising a surface layer and a crushed stone roadbed material.
Fig. 2 (c) is a conventional pavement of a fine-grained asphalt mixture (no water permeability) as a general pavement, and Fig. 2 (d) is a water-permeable pavement of an open-size asphalt mixture as a conventional general pavement. (The pavement which is the base body of FIGS. 2 (a) and 2 (b) and is not filled with the fine silica sand 4, 4a...), FIG. 2 (e) is the natural soil of the local board, and these are the objects of comparative measurement. did.
[0026]
[Table 6]

[0027]
Table 7 shows the results of measurements from August 22, 2001 to August 30, 2001, and Tables 8 and 9 show the results of measurements on August 22 and 23, respectively, for the purpose of measuring the rise in road surface temperature. indicate.
[0028]
[Table 7]

[0029]
[Table 8]

[0030]
[Table 9]

[0031]
Based on the measurement results of Tables 7 to 9, when the road surface temperature rise suppression ability of each pavement is compared, the temperature rise suppression of the road surface temperature using the porous surface layer filled with the fine silica sand 4, 4a of the present invention is suppressed. In the pavement with functions (thick solid line, broken line), the temperature rises compared to the conventional general fine-grained asphalt pavement (thin solid line) and open-graded asphalt pavement (permeable asphalt pavement) (dotted line). Could be suppressed.
[0032]
For example, the maximum temperature, the porosity of 25% open-graded asphalt pavement in fine silica sand 4, 4a ... of the pavement volume 1 m ³ pavement 16 ° C. lower the maximum temperature of the road surface was 160kg filled per the porosity of 15% It was possible to reduce the temperature by 8 ° C. with a pavement filled with 80 kg per 1 m ³ of fine silica sand, 4a, etc. on an open-graded asphalt pavement.
Further, in order to maintain the temperature rise, the pavement having the function of suppressing the temperature rise of the road surface temperature using the porous surface layer filled with the fine silica sand 4 of the present invention, 4a. The temperature was always lower than that of the grain-size asphalt pavement and the open-size asphalt pavement (water-permeable asphalt pavement), and the effect of suppressing the increase in road surface temperature could be expressed continuously.
[0033]
【The invention's effect】
In short, the present invention provides a porous asphalt pavement 2 having a water permeation function with a particle size of 10 μm or more and an average particle size of about 80 to 200 μm. Since the fine silica sand 4, 4 a ... Having pumping water is filled in the voids of the asphalt pavement 2 and the fine silica sand 4, 4 a ... After filling is made into an unsolidified state , the moisture is asphalt which is a porous surface layer in the road surface structure. Water is retained in the continuous fine voids formed by the fine silica sand 4, 4a ... filled in the voids in the pavement 2 and the heat is removed from the surroundings as the water evaporates near the surface of the asphalt pavement 2, thereby making it porous It is possible to suppress the surface temperature rise of the surface layer, and further, the continuous movement of the moisture due to capillary action (pumping action) is generated in the continuous fine voids formed in the porous surface layer. Evaporation of water, evaporation heat taken from the peripheral, it is possible to continue inhibiting elevation of the surface temperature, thus it is possible to suppress the heat island phenomenon.
[0034]
Since the fine particles have a particle diameter of 10 μm or more, continuous fine voids having water retaining and pumping functions can be easily formed without closing the voids in the asphalt pavement 2.
[0035]
Since the fine particles are made of fine silica sand 4, 4a, etc., environmental protection can be achieved by using the fine silica sand 4, 4a, which is industrial waste sludge.
[0036]
Since the fine silica sands 4 and 4a have an average particle size of 80 to 200 μm, the fine silica sands 4 and 4a which are generally disposed of in large quantities can be used.
[0037]
Since the porous asphalt pavement 2 has voids of 15 to 25% by volume percentage, the present invention can also be implemented for general pavement means.
[0038]
Since 80 to 160kg of fine silica sand 4, 4a ... is filled in the voids per 1m ³ of volume of asphalt pavement 2, the surface of asphalt pavement 2 is filled with fine silica sand 4, 4a ... to activate the evaporation action. I can do it.
[0039]
Since the pavement road surface structure is composed of the lower layer roadbed 1 and the surface layer asphalt pavement 2 according to claim 1, 2 or 3 , the roadbed 1 has water retention, and the roadbed 1 is the same as the asphalt pavement 2. It has a water retention function, and can easily replenish the water vaporized, retained and pumped by the asphalt pavement 2 from the roadbed 1 and can continuously achieve the evapotranspiration action for a long time.
[0040]
Since the roadbed 1 is filled with the same fine particles as the asphalt pavement 2 or fine silica sand 4, 4a, etc., the continuous fine gap between the roadbed 1 and the asphalt pavement 2 is formed without any boundary, and the continuity of the water retention and pumping function is increased. Even if the fine particles or fine silica sand 4, 4 a... Falls in the roadbed 1, the fine ground or fine silica sand 4, 4 a. The water retention function can be easily maintained and regenerated.
[0041]
After the formation of porous asphalt pavement 2 having a water permeation function, mineral fine particles or fine silica sand 4, 4a... Are sprinkled on the surface of asphalt pavement 2 to impart vibrations from the surface side or to the surface. Since the fine particles or fine silica sand 4, 4a, etc. are filled in the gaps of the asphalt pavement 2, the asphalt pavement 2 can be easily filled with the fine particles or fine silica sand 4, 4a, etc. Its practical effect is enormous.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing a schematic configuration of a road surface structure according to the present invention.
FIG. 2 is a cross-sectional view showing the structure of various test roads.
[Explanation of symbols]
1 Subbase 2 Asphalt pavement 3, 3a ... Aggregate 4, 4a ... Fine silica sand

Claims (5)

In a porous asphalt pavement having a water permeation function, a fine silica sand having a particle size of 10 μm or more and an average particle size of about 80 to 200 μm, having water retention in a filled state, water permeability and water pumping An asphalt pavement having a function to suppress the rise in road surface temperature, characterized in that the fine silica sand after filling is filled in the voids of the asphalt pavement.   2. The asphalt pavement having a road surface temperature rise suppressing function according to claim 1, wherein the porous asphalt pavement has a void of 15 to 25% by volume percentage. ^{3. The} asphalt pavement having a road surface temperature rise suppressing function according to claim 2, wherein the gap is filled with fine silica sand of 80 to 160 kg per 1 m ³ of the volume of the asphalt pavement.   Asphalt having a road surface temperature rise suppression function, wherein the pavement surface structure is composed of a lower layer roadbed and a surface asphalt pavement according to claim 1, 2 or 3, wherein the roadbed has water retention. Paved road surface structure.   5. The asphalt pavement road surface structure having a road surface temperature rise suppressing function according to claim 4, wherein the roadbed is filled with the same fine particles or fine silica sand as the asphalt pavement.

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